JP5073322B2 - Defrost control device for cooling storage - Google Patents

Description

  The present invention relates to a defrost control device in a cooling storage.

Off-cycle that performs so-called natural defrosting by leaving the chiller in a state where the refrigeration system is stopped and the supply of refrigerant is stopped as a method of defrosting operation that removes frost adhering to the cooler in the cooling storage A defrosting method is known (see, for example, Patent Document 1). In this method, generally, the temperature of the cooler is detected, and the defrosting operation is terminated when the detected temperature reaches a predetermined temperature.
Japanese Patent Laid-Open No. 4-217663

However, in the above method, when the set temperature in the refrigerator is low or the outside air temperature is low, the temperature rise of the cooler becomes a very slow speed. However, there was a risk that the defrosting operation time would become unnecessarily long and adversely affect the stored items.
Even in the heating defrosting method in which the cooler is heated with a heater or hot gas, the temperature rise of the cooler tends to become dull when the internal set temperature or the outside air temperature is low.
The present invention has been completed based on the above circumstances, and its purpose is to minimize the defrosting operation time.

As a means for achieving the above object, the invention of claim 1 is characterized in that the refrigerant is supplied to the cooler by driving the refrigeration apparatus, and the cold air generated by heat exchange with the cooler is circulated and circulated in the warehouse. In the cooling storage where the cooling operation to be cooled is performed, and the defrosting operation to remove the frost formation of the cooler is performed in the middle thereof, the temperature detection means for detecting the temperature of the cooler, and the defrosting Based on the detection temperature of the temperature detection means on condition that the detection temperature of the temperature detection means exceeds 0 ° C. and is equal to or higher than a predetermined temperature near 1.5 ° C. at regular time intervals after the start of operation. The calorific value calculating means for calculating the calorific value given to the cooler during the predetermined time, the calorific value accumulating means for accumulating the respective calorific values, and the integrated value obtained by the calorific value integrating means reach a predetermined reference value. The defrosting operation is terminated. Resuming the defrosting end judging means for cooling operation, has a feature where the has a configuration that is provided.

  According to a second aspect of the present invention, in the first aspect of the present invention, the defrosting end determining means is configured such that when the temperature detected by the temperature detecting means exceeds a predetermined value, the integrated value of the heat quantity becomes a reference value. It has a feature in that it has a function to end the defrosting operation even though it has not been reached.

  The invention according to claim 3 is the off-cycle defrosting operation according to claim 1 or 2, wherein the defrosting operation defrosts the cooler by continuing the stop state of the refrigeration apparatus. In this case, the heat amount integrating means is characterized in that it is executed only when the internal set temperature is not higher than a predetermined value or the low temperature condition is that the outside air temperature is not higher than a predetermined value.

<Invention of Claim 1>
When the defrosting operation is started, the amount of heat given to the cooler during the predetermined time is calculated based on the temperature detected by the temperature detecting unit by the heat amount calculating unit at every predetermined time interval, and each amount of heat is converted into the amount of heat. When the integrated value is integrated and the integrated value reaches a predetermined reference value, it is considered that the defrosting is completed by the defrosting end determining unit, the defrosting operation is ended, and the cooling operation is restarted.
That is, in the present invention, the defrosting is completed when the amount of heat given to the cooler to defrost after the start of the defrosting reaches the reference value, so the temperature of the conventional cooler is removed. Compared with the case where the defrosting is completed after waiting for the frost end temperature to be reached, the defrosting time can be greatly shortened particularly when the temperature of the cooler is kept low. Therefore, adverse effects on stored foods and the like are prevented.

<Invention of Claim 2>
Depending on the timing of defrosting, defrosting may be completed in a short time due to a small amount of frost formation. At that time, even if the cooler is likely to become cold, the cooler temperature may rise to the defrosting end temperature relatively early, and then wait for the cooler itself to rise in temperature. Is selected as the end of defrosting. On the contrary, it is avoided that the defrosting time is excessively taken by the heat amount integration control.

<Invention of Claim 3>
In the off-cycle defrosting operation, it is remarkable that the temperature rise of the cooler takes time when the internal set temperature or the outside air temperature is low. Under such conditions, the accumulated heat amount applied to the cooler Performing control to end the defrosting is extremely effective for shortening the defrosting time.

<Embodiment 1>
A first embodiment of the present invention will be described with reference to FIGS. In this embodiment, a horizontal (table type) cooling storage is illustrated.
As shown in FIG. 1, the cooling storage of the present embodiment has a storage body 10 made of a heat insulating box that is open on the front surface, and the inside is a storage chamber 11, and the front opening of the storage chamber 11 is insulated. A door (not shown) is mounted so as to be swingable.
A machine room 13 is provided on the left side when viewed from the front of the main body 10, and an adiabatic cooler room 15 communicating with the storage room 11 is formed over the upper part of the machine room 13. 15 is equipped with a cooler 16 and a cooling fan 17. On the other hand, in a space extending from the lower side to the left side of the cooler chamber 15, a refrigeration apparatus 20 including a compressor 21, a condenser 22 and the like is accommodated and circulated and connected by a cooler 16 and a refrigerant pipe.
Further, a drain pan 24 for receiving defrost water from the cooler 16 is provided on the bottom surface of the cooler chamber 15, and a drain pipe 24 </ b> A suspended from the deepest portion of the drain pan 24 projects into the machine chamber 13, A drain hose 25 is connected to the protruding end and led to a predetermined drainage location.

  The cooling operation is performed by driving the compressor 21 and the cooling fan 17. As shown by the arrow in FIG. 1, the internal air sucked from the suction port 27 on the lower side of the duct 26 is cooled. The inside of the storage chamber 11 is cooled by generating a circulating flow in which cold air is generated by heat exchange while flowing upward in the vessel 16 and this cold air is blown out from the outlet 28 to the ceiling side of the storage chamber 11. The During this time, when the internal temperature detected by the internal thermistor 29 provided in the vicinity of the suction port 27 becomes lower than the predetermined internal temperature, the drive of the compressor 21 and the cooling fan 17 is stopped, and the reverse When the internal temperature becomes higher than the internal set temperature, the compressor 21 and the cooling fan 17 are repeatedly driven, so that the interior of the storage chamber 11 is maintained substantially at the internal set temperature. (See FIG. 4).

On the other hand, the defrosting operation is performed during the cooling operation. The defrosting format of this embodiment is an off-cycle defrosting format that performs natural defrosting with the compressor 21 stopped, and is executed by the all-day timer 31 (FIG. 2) every 3 hours, for example. ing.
In addition, a defrosting thermistor 33 that detects the temperature of the cooler 16 is attached to the cooler 16, and the detection temperature of the defrosting thermistor 33, that is, the temperature of the cooler 16 is determined in advance during the defrosting operation. When the set temperature is reached, it is considered that the defrosting has been completed. In the present embodiment, the set temperature is set to “5 ° C.”, and this set temperature is hereinafter referred to as the defrost end temperature.

In the present embodiment, under the condition that the temperature of the cooler 16 may be kept low, it is not the case where the cooler 16 rises to the defrosting end temperature, but defrosting is started after defrosting is started. When the amount of heat given to the cooler 16 reaches a predetermined value, it is possible to execute control that considers that defrosting has been completed.
In the present embodiment, as one of the low temperature conditions, the internal set temperature is taken into consideration, and the above control is performed only when the internal set temperature is “0 ° C. or less”.
The defrosting operation with the same control is performed based on a program stored in the control device 40 shown in FIG. 2. On the input side of the control device 40, an all-day timer 31, an in-chamber set temperature input are input. The part 32 and the defrosting thermistor 33 are connected. The control device 40 calculates the amount of heat Qi (J) applied to the cooler 16 during the same fixed time based on the temperature detected by the defrosting thermistor 33 at regular time intervals after the start of the defrosting operation. Computation unit 41, calorific value accumulating unit 42 for accumulating each calorific value Qi, and the accumulated value Qa are compared with a predetermined calorific value reference value Qd. A defrosting end determination unit 43 that outputs a frost end signal is provided.

  Specifically, the calorific value calculation unit 41 calculates the product of the difference between the detected temperature of the defrosting thermistor 33 and “0 ° C.” and the elapsed time (10 seconds) every 10 seconds. However, the calorific value calculation unit 41 performs the above calculation only when the temperature detected by the defrosting thermistor 33 is 1.5 ° C. or higher. In consideration of variations in the detection function of the defrosting thermistor 33, it means that the amount of heat is calculated only when the temperature of the cooler 16 surely exceeds 0 ° C.

  The heat quantity reference value Qd set in the defrosting end determination unit 43 is “1600”. This is determined based on the empirical amount of heat required to complete the defrosting of the cooler 16. Further, the defrosting end signal is output to the cooling operation control unit 45, and is switched to the cooling operation. Further, the defrosting end determination unit 43 outputs a defrosting end signal when the defrosting thermistor 33 detects a defrosting end temperature of 5 ° C. even before the integrated value Qa reaches the heat quantity reference value Qd. It is like that.

Hereinafter, the operation of the present embodiment will be described with reference to the flowchart of FIG. 3 and the timing chart of FIG.
Here, the case where the internal set temperature is “−3 ° C.” is illustrated, that is, the defrosting operation control is executed by being in a low temperature condition, and the defrosting operation is performed every 3 hours. .
In FIG. 4, during the cooling operation, as described above, the compressor 21 and the cooling fan depend on whether the internal temperature detected by the internal thermistor 29 is higher or lower than the internal set temperature (−3 ° C.). The drive of 17 and its stop are controlled, and the inside of the storage chamber 11 is maintained at the set temperature (−3 ° C.).

  When the defrosting start timing Td is reached during the cooling operation, the compressor 21 is stopped, and the off-cycle defrosting is executed while the temperature of the cooler 16 (the temperature detected by the defrosting thermistor 33) gradually increases. On the other hand, when the defrosting is started, as shown in FIG. 3, the detected temperature of the defrosting thermistor 33 is taken in step S2 every 10 seconds (step S1 is “Yes”). The process does not proceed to the next step until the detected temperature reaches 1.5 ° C. or higher. When the detected temperature is 1.5 ° C. or higher (step S3 is “Yes”), the defrosting thermistor is used in the calorific value calculation unit 41 on condition that the detected temperature does not exceed 5 ° C. (step S4 is “No”). The amount of heat Qi, which is the product of the difference between the detected temperature of 33 and the difference of “0 ° C.” and the elapsed time (10 seconds), is calculated (step S5), and then the calculated amount of heat Qi is integrated in the amount-of-heat integration unit 42. (Step S6).

Thereafter, in principle, the amount of heat Qi is calculated every 10 seconds, and the calculated values are integrated. During this time, if the detected temperature of the defrosting thermistor 33 is sometimes less than 1.5 ° C. (step S3 is “No”), the calculation of the amount of heat and its integration are not performed. After that, when the integrated value Qa reaches a predetermined reference value Qd, it is considered that the defrosting has been completed, and a defrosting end signal is sent from the defrosting end determination unit 43 to the cooling operation control unit 45 (step). S8) The cooling operation is resumed.
Even if the integrated value Qa does not reach the reference value Qd, if the defrosting thermistor 33 detects the defrosting end temperature of 5 ° C. (step S4 is “Yes”), it is considered that the defrosting is completed. Similarly, a defrosting end signal is sent from the defrosting end determination unit 43 to the cooling operation control unit 45 (step S8), and the cooling operation is restarted.

  As in this case, when off-cycle defrosting is performed every 3 hours under the condition that the internal temperature is “−3 ° C.” and the outside air temperature is room temperature (25 ° C.), In the case where the defrosting is completed after waiting for the temperature to reach the defrosting end temperature (5 ° C.), it takes “168 minutes” for the defrosting time, as in the present embodiment. When the amount of heat given to the cooler 16 to defrost after the start of defrosting reaches a predetermined value, the defrosting time is “56 minutes”. It has been confirmed by experiments that the defrosting time has decreased to 1/3.

  As described above, according to the present embodiment, the defrosting ends when the amount of heat given to the cooler 16 to defrost after the start of the defrosting reaches the reference value. According to this method, there is a possibility that a slight amount of frost may remain partially, but since the specified amount of heat can be reliably applied, most of the frost can be melted and the desired defrosting capacity can be reliably obtained. It is done. As a result, the defrosting time is reduced especially in the case where the temperature of the cooler 16 is kept at a low temperature as compared with the case where the temperature of the cooler 16 is kept low after waiting for the temperature of the conventional cooler 16 to reach the defrosting end temperature. It can be greatly shortened. Therefore, adverse effects on stored foods and the like are prevented.

  On the other hand, depending on the timing of defrosting, the defrosting may be completed in a short time because the amount of frost formation is small. At that time, the temperature of the cooler 16 may rise to the defrosting end temperature relatively early even if the cooler 16 is likely to become low temperature. In this case, the temperature of the cooler 16 itself It is selected to wait for the rise to be regarded as the end of defrosting. On the contrary, it is avoided that the defrosting time is lengthened by the heat accumulation control.

<Embodiment 2>
Next, Embodiment 2 of the present invention will be described. In the first embodiment, the case where the internal set temperature is low is illustrated as a condition that the temperature of the cooler 16 tends to be low. However, in the second embodiment, the case where the outside air temperature is low is selected.
Therefore, as shown by the chain line in FIG. 2, the outside temperature temperature thermistor 50 is connected to the input side of the control device 40, and when the temperature detected by the thermistor 50 is equal to or lower than a predetermined value, the first embodiment is shown. Defrost control is performed by a heat integration method.

In addition, when one of the conditions that the internal set temperature is equal to or lower than the predetermined value and the outside air temperature is equal to or lower than the predetermined value is satisfied, or when both conditions are satisfied, You may make it perform defrost control.
Further, as the outside temperature thermistor 50, a clogged thermistor provided at the outlet of the condenser 22 may also be used.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention, and further, within the scope not departing from the gist of the invention other than the following. Various modifications can be made.
(1) In the case of defrosting control of the heat amount integration type by the off-cycle defrosting method, during the defrosting operation, the cooler temperature is considered to be substantially equal to the internal temperature, so the temperature of the cooler is calculated to calculate the amount of heat. In order to detect this, an internal thermistor may be substituted.
(2) On the microcomputer board, for simplification, the “heat amount” may be indicated by a value not including the elapsed time (10 seconds). In this case, “160” is stored as the heat amount reference value. .
(3) The calorific value reference value shown in the above embodiment is an example, and the optimum calorific value required to complete the defrosting of the cooler is tested according to conditions such as the capacity of the cooler and the refrigerating capacity. It may be determined based on experience.
(4) Furthermore, numerical values such as the defrosting operation interval (every 3 hours) and the calorific value calculation time interval (10 seconds) exemplified in the above embodiment can be changed to other numerical values.

(5) The present invention can also be applied to a heating defrosting system in which the cooler is heated with a heater or hot gas. Even in the case of the heating defrosting method, if the internal temperature or the outside air temperature is low, the temperature rise of the cooler may be delayed even if it is not as high as the off-cycle defrosting method. By controlling the defrosting, it is possible to suppress the defrosting time accurately.
(6) In the case of the off-cycle defrosting method, when the interior lamp is turned on and the cooling fan is driven, the heat generated by the interior lamp can be used for defrosting, and the defrosting time can be shortened. It is done.

Sectional drawing which shows the internal structure of the cooling storage which concerns on Embodiment 1 of this invention Block diagram of defrost control system Flow chart of defrost control Driving timing chart

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Storage chamber 16 ... Cooler 17 ... Cooling fan 20 ... Refrigeration device 31 ... All day timer 32 ... Inside temperature setting part 33 ... Defrosting thermistor (temperature detection means) 40 ... Control device 41 ... Calorific value calculation part (calorie calculation) Means) 42 ... heat amount integrating part (heat amount integrating means) 43 ... defrosting end determining part (defrosting end determining means)

Claims (3)

A refrigerant is supplied to the cooler by driving the refrigeration apparatus, and a cooling operation is performed in which the cold air generated by heat exchange with the cooler is circulated and circulated in the warehouse, and the cooling is performed in the middle of the cooling operation. In the cooling storage where the defrosting operation to remove the frosting of the vessel is performed,
Temperature detecting means for detecting the temperature of the cooler;
At a certain time interval after the start of the defrosting operation, the detected temperature of the temperature detecting means is set to the detected temperature of the temperature detecting means on condition that the detected temperature of the temperature detecting means exceeds 0 ° C and is equal to or higher than a predetermined temperature near 1.5 ° C. A calorific value calculating means for calculating the calorie given to the cooler during the predetermined time based on;
A calorific value accumulating means for accumulating the calorific values;
A defrosting end determining means for ending the defrosting operation and restarting the cooling operation when the integrated value obtained by the heat amount integration means reaches a predetermined reference value;
A defrosting control device for a cooling storage, comprising: The defrosting end determining means has a function of ending the defrosting operation when the temperature detected by the temperature detecting means is equal to or higher than a predetermined value, even though the integrated value of the heat amount has not reached the reference value. The defrosting control device for a cooling storage according to claim 1, wherein In the case where the defrosting operation is an off-cycle defrosting operation in which the cooler is defrosted by continuing the stopped state of the refrigeration apparatus, the calorific value integrating means has an internal set temperature of a predetermined value or less 3. The defrosting control device for a cooling storage according to claim 1, wherein the defrosting control device is executed only when the outside air temperature is a low temperature condition equal to or lower than a predetermined value.

Images